Container DNS and service discovery in Docker - Mini Project: Build & Apply

Container DNS and Service Discovery with Docker

📖 Scenario: You are setting up a small Docker network where two containers can find each other by name. This is like having two friends in a room who can call each other by their names instead of phone numbers.We will create two containers: a simple web server and a client that will ping the server using its container name. This shows how Docker's built-in DNS helps containers discover each other easily.

🎯 Goal: Build a Docker network with two containers named webserver and client. The client container will use the container name webserver to ping and confirm it can reach the webserver container using Docker's DNS service discovery.

📋 What You'll Learn

Create a Docker network named my_network

Run a container named webserver using the nginx image connected to my_network

Run a container named client connected to my_network

Use the ping command inside the client container to ping webserver

Display the ping result to confirm connectivity

💡 Why This Matters

🌍 Real World

In real projects, containers need to find and talk to each other easily. Docker's DNS service discovery lets containers use simple names instead of IP addresses, making communication reliable and easier to manage.

💼 Career

Understanding container networking and service discovery is essential for DevOps roles, cloud engineers, and developers working with microservices and container orchestration.

1

Create a Docker network

Create a Docker network called my_network using the command docker network create my_network.

Docker

# Your code here

Need a hint?

Think of a Docker network as a private room where containers can talk to each other by name.

2

Run the webserver container on the network

Run a container named webserver using the nginx image connected to the my_network network with the command docker run -d --name webserver --network my_network nginx.

Docker

docker network create my_network
# Your code here

Need a hint?

Use --name to name the container and --network to connect it to the network.

3

Run the client container on the network

Run a container named client connected to the my_network network using the alpine image with the command docker run -it --rm --name client --network my_network alpine sh. Then install ping inside the container with apk add --no-cache iputils.

Docker

docker network create my_network
docker run -d --name webserver --network my_network nginx
# Your code here

Need a hint?

The alpine image is small and you need to add ping manually using apk.

4

Ping the webserver container from the client

Inside the client container shell, run the command ping -c 3 webserver to send 3 ping requests to the webserver container and confirm connectivity.

Docker

docker network create my_network
docker run -d --name webserver --network my_network nginx
docker run -it --rm --name client --network my_network alpine sh
apk add --no-cache iputils
# Your code here

Need a hint?

If you see lines starting with PING webserver and replies, it means the client found the webserver by name.